Temperature Gradient Sensing in Portable Electronic Devices

ABSTRACT

An electronic device housing encloses a temperature sensing system including a temperature sensor and a differential temperature probe. The differential temperature probe includes a flexible substrate defining two ends. A first end is thermally coupled to the temperature sensor and a second end is thermally coupled to a surface, volume, or component of the electronic device. The temperature probe is an in-plane thermopile including a series-coupled set of thermocouples extending from the first end to the second end. A temperature measured at the temperature sensor can be a first measured temperature and a voltage difference across leads of the differential temperature probe can be correlated to a differential temperature relative to the first measured temperature. A sum of the differential temperature and the first measured temperature is a second measured temperature, quantifying a temperature of the second end of the differential temperature probe.

TECHNICAL FIELD

This application relates to temperature sensing in portable electronicdevices and, in particular, to systems and methods for preciselydetermining a temperature gradient between two or more discretelocations within a portable electronic device housing.

BACKGROUND

An electronic device can include a temperature sensor. An output fromthe temperature sensor can be used to calibrate, or adjust, an outputfrom another sensor or subsystem of the electronic device that issensitive to changes in temperature.

Many electronic devices include multiple sensors or subsystems that aresensitive to temperature. However, because conventional temperaturesensors reserve volume within an electronic device housing, and can beexpensive components, it is often impractical to include a temperaturesensor dedicated to each temperature-dependent sensor or subsystem of anelectronic device. As a result, at least some sensors or subsystems ofconventional electronic devices are operated in a suboptimal,temperature-dependent, manner.

SUMMARY

Embodiments described herein take the form of a differential temperaturesensor probe for a temperature sensor of a portable electronic device.The temperature sensor is configured to measure absolute temperature ofa surface thereof. The temperature probe is configured to generate avoltage corresponding to a temperature gradient between a first end ofthe probe and a second end of the probe. The temperature sensor can bedisposed within an electronic device housing. A first end of the probecan be coupled to the temperature sensor and a second end of the probecan be coupled to any suitable surface, whether internal or external, ofthe electronic device. As a result of this construction, an accurateabsolute temperature measurement can be obtained for any surface orvolume of an electronic device.

For such embodiments, the temperature sensor can be any suitabletemperature sensor but in many examples, the temperature sensor is ahigh-precision and high-accuracy absolute temperature sensor thatdefines a sensing surface (e.g., an external surface of an encapsulationor potting enclosing electronics and/or integrated circuits cooperatingto define the temperature sensor as an electronic component). In thisconstruction, the temperature sensor can be configured to measure atemperature, at any given sampling time or sampling rate, of any surfaceor volume to which the sensing surface is exposed.

In these examples, the temperature sensor probe includes a thin-filmsubstrate defining a first end thermally coupled to the temperaturesensor and a second end thermally coupled to a surface within theportable electronic device. An in-plane thermopile is defined on thethin-film substrate. The in-plane thermopile is defined by a conductivetrace disposed in a serpentine pattern that oscillates between the firstend and the second end. In this manner, the conductive trace defines anarray of thermocouples conductively coupled in series. Each thermocoupleof the series includes a first portion that extends from the first endto the second end of the thin-film substrate and a second portion thatextends from the second end to the first end of the thin-film substrate.The first portion and the second portion are joined at a junctiondefined at the second end.

As a result of this construction, the in-plane thermopile is configuredto generate a voltage corresponding to a temperature difference betweenthe temperature sensor (which takes the same temperature as the firstend of the low-profile substrate) and the surface within the portableelectronic device.

In some examples, the conductive trace is defined on a single side ofthe thin-film substrate. In other embodiments, the conductive trace canbe defined on a top surface (e.g., a first surface) and a bottom surface(e.g., a second surface) of the thin-film substrate. In the second case,vias can pass through the thin-film substrate to electrically couplelinear traces on the top surface to linear traces on the bottom surface.In this manner, the conductive trace forms a single electrical circuitcomponent that defines a conductive path that oscillates from the firstend to the second end.

The various linear traces defining the single conductive trace can beformed from different conductive materials in order to leverage theSeebeck effect. In particular, traces extending from the first end tothe second end (e.g., a first set of linear conductive traces) can beformed from a first conductive material, such as a metal or metal alloy.Similarly, traces extending from the second end to the first end can beformed from a second conductive material, such as a different metal ormetal alloy. In typical examples, the Seebeck ratio defined relative tothe first conductive material and the second conductive material isnegative. For example, the first conductive material may be constantanand the second conductive material may be chromel, another nickel alloy,copper or another metal. Example constructions include Type-Ethermocouples (e.g., constantan-chromel) and/or Type-T thermocouples(e.g., constantan-copper). Other constructions include thermocouples ofother types.

In many embodiments, the thin-film substrate is formed from a flexiblematerial (e.g., polyimide, polyethylene terephthalate, polycarbonate,plastics, acrylics, liquid crystal polymers, and so on). In manyimplementations, the thin-film substrate has a high aspect ratio. As oneexample, in some embodiments, the aspect ratio may be greater than two.In other examples, the aspect ratio may be greater than ten.

As a result of both flexibility and relative length, and subject only tophysical properties of the thin-film substrate (e.g., length, width,depth, minimum bend radius, and so on), the second end can be positionedsubstantially anywhere within an electronic device housing. In otherexamples, the second end can be positioned external to an electronicdevice housing.

Further embodiments described herein take the form of a temperaturesensing system for an electronic device. The temperature sensing systemcan include a temperature sensor defining an exterior surface and adifferential temperature probe thermally coupled to the exterior surfaceof the temperature sensor. As with other embodiments described herein,the differential temperature probe can have a high aspect ratio (e.g.,an aspect ratio greater than 1) and can be formed from a thin-filmmaterial that is flexible.

In typical constructions, the differential temperature probe is definedby a flexible substrate in turn defining a first end and a second end.The second end is separated from the first end by a length of theflexible substrate. The first end of the substrate is thermally coupledto the exterior surface of the temperature sensor. The second end of thesubstrate can be coupled to and/or exposed to any suitable surface orvolume. In typical implementations, the second end of the substrate canbe coupled to an electronic component associated with a system, sensor,or subsystem of a portable electronic device.

The differential temperature probe is also defined, in part, by aconductive trace that defines a conductive path between a pair of leadsdisposed on the first end. The conductive trace is disposed in aserpentine pattern between the first end and the second end of thesubstrate. The conductive trace includes (1) a first set of tracesdisposed from a first conductive material extending from the first endto the second end and (2) a second set of traces disposed from a secondconductive material extending from the second end to the first end.

The first conductive material is different from the second conductivematerial in order to leverage the Seebeck effect. In some embodiments,the first and second conductive materials may be different nickelalloys. In other constructions, the first and second conductivematerials may be different metals, semiconductors, metal alloys, orpairings thereof.

As a result of this construction, a voltage difference between the pairof leads can be correlated to a temperature difference (a temperaturegradient) between the exterior surface of the temperature sensor and thesecond end of the differential temperature probe. In further examplesand embodiments, a temperature measurement obtained from the temperaturesensor sampled at the same time a voltage difference between the leadsof the differential temperature sensor can be used to calculate twodifferent temperatures and/or a temperature and a temperaturedifference. In another phrasing, the voltage difference taken at aparticular sampling time corresponds to a temperature gradient acrossthe differential temperature probe (e.g., a temperature differencebetween the first end and the second end). An absolute temperaturemeasurement taken at the same sampling time by the temperature sensorcorresponds to an absolute temperature of the temperature sensor and,additionally, of the first end of the temperature gradient. By combiningthese two measurements, absolute temperature of the second end of thetemperature probe can be determined.

For example, if the exterior surface of the temperature sensor isthermally coupled to a processor of an electronic device and the secondend of the differential temperature probe is coupled to a battery of thesame electronic device, the temperature sensor can be configured tooutput two discrete temperature measurements, one temperature associatedwith the processor and one temperature associated with the battery. Asthese temperature measurements are sampled relative to one another viathe differential temperature probe, no further calibration or adjustmentof the temperature values is required.

Additional embodiments described herein take the form of a method ofoperating a temperature sensing system for an electronic device todetermine a first temperature and a second temperature of the electronicdevice, the method including operations such as: sampling a temperaturesensor to obtain the first temperature; sampling a voltage differencebetween leads of a differential temperature probe thermally coupled tothe temperature sensor and thermally coupled to a target surface of theelectronic device; converting the voltage difference to a temperaturedifference; and summing the temperature difference and the firsttemperature to obtain the second temperature. Related embodiments caninclude multiple different temperature probes to obtain multipledifferential temperature measurements which, in turn, can be correlatedto multiple discrete temperature measurements.

In still further examples, average temperature of multiple points can bedetermined by leveraging a temperature probe as described herein. Inthese examples, the temperature probe can be formed into a shape thatdefines multiple distal ends (e.g., multiple second portions). Anexample shape is a hub and spoke shape or a cross shape. In the firstexample, a hub of the hub and spoke shape can be a first end of thetemperature probe that includes a number of junctions of a number ofthermocouples. Each distal end of each spoke of the hub and spoke shapecan be coupled to, embedded into, or otherwise thermally coupled todifferent locations within an electronic device housing. As a result ofthis construction, a voltage difference between leads of the hub andspoke differential temperature probe can correspond to an averagetemperature of all spokes of the probe. In other words, an averagetemperature within the electronic device housing can be determined.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will now be made to representative embodiments illustrated inthe accompanying figures. It should be understood that the followingdescriptions are not intended to limit this disclosure to one includedembodiment. To the contrary, the disclosure provided herein is intendedto cover alternatives, modifications, and equivalents as may be includedwithin the spirit and scope of the described embodiments, and as definedby the appended claims.

FIG. 1 depicts an example portable electronic device that canincorporate a temperature sensing system, such as described herein.

FIG. 2 depicts a simplified system diagram of a temperature sensingsystem, such as described herein, disposed within a housing of aportable electronic device.

FIG. 3A depicts a differential temperature probe of a temperaturesensing system, such as described herein.

FIG. 3B depicts a schematic representation of the differentialtemperature probe of FIG. 3A.

FIG. 4 is an assembly view of a differential temperature probe of atemperature sensing system, as described herein.

FIGS. 5A-5G depict example constructions of a differential temperatureprobe as described herein.

FIG. 6A is a flowchart depicting example operations of a method ofmanufacturing a differential temperature probe, such as describedherein.

FIG. 6B is a flowchart depicting example operations of a method ofmanufacturing a differential temperature probe, such as describedherein.

FIG. 7 is a flowchart depicting example operations of a method ofmanufacturing a temperature sensing system, such as described herein.

FIG. 8 is a flowchart depicting example operations of a method ofoperating a temperature sensing system, such as described herein.

The use of the same or similar reference numerals in different figuresindicates similar, related, or identical items.

The use of cross-hatching or shading in the accompanying figures isgenerally provided to clarify the boundaries between adjacent elementsand also to facilitate legibility of the figures. Accordingly, neitherthe presence nor the absence of cross-hatching or shading conveys orindicates any preference or requirement for particular materials,material properties, element proportions, element dimensions,commonalities of similarly illustrated elements, or any othercharacteristic, attribute, or property for any element illustrated inthe accompanying figures.

Additionally, it should be understood that the proportions anddimensions (either relative or absolute) of the various features andelements (and collections and groupings thereof) and the boundaries,separations, and positional relationships presented therebetween, areprovided in the accompanying figures merely to facilitate anunderstanding of the various embodiments described herein and,accordingly, may not necessarily be presented or illustrated to scale,and are not intended to indicate any preference or requirement for anillustrated embodiment to the exclusion of embodiments described withreference thereto.

DETAILED DESCRIPTION

Embodiments described herein relate to systems and methods for sensingabsolute temperature at multiple points (e.g., either absolutetemperature or temperature gradients) by levering an output of a singletemperature sensor. As used herein the phrase “absolute temperature”(or, more simply, “temperature”) refers to a digital value or analogsignal (or sequence, time series, or sample set thereof) that quantifiesthermal energy of a body, surface, or volume in a standard unit (e.g.,Celsius, Fahrenheit, Kelvin, and so on) or a non-standard unit (e.g., agraduated relative scale). For simplicity of description, theembodiments that follow reference temperature measurements in degreesCelsius, but it may be appreciated that this is merely oneimplementation and other scales, units, or proportional values may beused in other embodiments.

More specifically, embodiments described herein reference temperaturesensing systems configured to detect, with high precision and accuracy,a temperature of each of one or more points (herein “probe locations”)relative to a reference temperature defined by a temperature sensordisposed within an enclosure of a portable or stationary electronicdevice.

Each probe location can be probed with a differential temperature probehaving two ends, one of which is thermally coupled (e.g., byinterfacing, with a thermal paste, or using another suitable method) tothe temperature sensor. As used herein, the phrase “differentialtemperature probe” refers to a structure or circuit configured togenerate a voltage proportionality related to a difference in absolutetemperature between two or more points.

In particular, as noted above, a first end of a differential temperatureprobe as described herein is thermally coupled to the temperature sensorand, by virtue thereof, is at the reference temperature, the “referencetemperature” being defined as a temperature detected by the temperaturesensor itself.

A second end of a differential temperature probe as described herein isthermally coupled to one respective probe location and, by virtuethereof, is at the absolute temperature of that respective probelocation.

As a result of this construction, a differential temperature probe asdescribed herein is configured to generate a voltage as a result of, andin proportion to, the temperature difference between the respectiveprobe location and the reference temperature which, in turn, can becorrelated to a “differential temperature,” which is a positive, zero,or negative temperature difference defined relative to the referencetemperature. As may be appreciated by a person of skill in the art, asum of the differential temperature and the reference temperature isequal to the absolute temperature of the probe location. In this manner,output from a single temperature sensor within a portable electronicdevice can be leveraged to accurately and precisely detect (and output)a temperature of each of multiple probe locations within or external toan electronic device housing.

More particularly, it may be appreciated that a probe location asdescribed herein can be any component, part, volume, surface, or bodyenclosed by, coupled to, or defined by an electronic device housing. Forexample, a probe location of a temperature sensing system can beinternal to an electronic device housing (e.g., within an internalvolume defined by the housing) whereas in other cases, a probe locationcan be external to an electronic device housing.

An internal probe location may be defined relative to a particularelectronic component within an electronic device housing, such as aprocessor, memory, battery, display, or input sensor. In other cases, anexternal probe location may be defined relative to an external surfaceof an electronic device housing, such as a cover glass surface, anexterior button or input device, or a back surface such as a backcrystal of a smart watch. It is appreciated that these foregoingexamples are not exhaustive; any suitable probe location can be selectedand suitable probe locations may vary from embodiment to embodiment, andfrom portable electronic device to portable electronic device.

Example portable electronic devices that can include a temperaturesensing system as described herein to detect and quantify absolutetemperature at one or more probe locations include, but are not limitedto: laptop computers; cellular phones; wearable electronic devices;accessory devices; and so on.

For simplicity of description, the embodiments that follow reference awearable electronic device as an example of a portable electronicdevice, but it may be appreciated that this is merely one example andthat in other implementations of embodiments described herein, otherportable or stationary electronic devices may be selected.

Broadly, a wearable electronic device incorporating a temperaturesensing system as described herein can detect absolute temperature ofmultiple discrete locations or volumes without requiring multipletemperature discrete temperature sensors. As a result, a wearableelectronic device can recover and/or reallocate substantial internalvolume otherwise conventionally allocated to multiple temperaturesensors and can be manufactured at lower cost without sacrificingperformance of sensors of subsystems of the wearable electronic devicethat are temperature dependent.

In addition, a wearable electronic device incorporating a temperaturesensing system as described herein may be able to detect absolutetemperature of components, surfaces, and/or volumes that a dedicatedtemperature sensor simply cannot reach. For example, in manyembodiments, a differential temperature probe (as described in greaterdetail below) may be implemented on a flexible thin-film substrate thatmay be routed to a probe location that is substantially smaller than,thinner than, or otherwise not able to be thermally coupled to aconventional temperature sensor. For example, a thin-film differentialtemperature probe may be routable to individual display layers of adisplay stack. In other cases, a thin-film differential temperatureprobe may be routed around, or through, other components within thewearable electronic device.

In other words, because of the ability of a thin-film differentialtemperature probe (as described herein) to be routed and/or placedsubstantially anywhere within a wearable electronic device housing, thetemperature sensor generating the reference temperature can also gainsubstantial placement flexibility. In this manner, the wearableelectronic device itself can be designed and manufactured with fewerpositional and/or component constraints; it may not be required toposition a temperature sensor in any particular location of the wearableelectronic device if a differential temperature probe, as describedherein, can be routed to any arbitrary probe location. Further, in someembodiments, multiple differential temperature probes can be thermallycoupled to a single temperature sensor. In such constructions, differentdifferential temperature probes can be routed to different probelocations and, in turn, can precisely and accurately detect temperatureof any number of probe locations within a wearable electronic device. Instill further examples, as may be appreciated by a person of skill inthe art, cost and design complexity savings achieved by incorporating atemperature sensing system as described herein can be used toincorporate a higher quality temperature sensor which, in turn, candramatically improve temperature differential detection performance ofall differential temperature probes.

For example, a conventional wearable electronic device may include afirst temperature sensor and a second temperature sensor. In oneexample, the first temperature sensor is thermally coupled to aprocessor of the conventional wearable electronic device and the secondtemperature sensor is thermally coupled to a battery of the conventionalwearable electronic device. The conventional electronic device mayleverage temperature measurements from these two sensors to inform oneor more operations or tasks related to the processor or the battery.

In this example construction, it may be appreciated that positionalconstraints for the first temperature sensor and the second temperaturesensor are well-defined; the first temperature sensor must be placedphysically proximate to the processor of the conventional wearableelectronic device and, likewise, the second temperature sensor must beplaced physically proximate to the battery. As may be appreciated by aperson of skill in the art, each of these positional constraintssubstantially informs design and cost of the overall wearable electronicdevice.

In many cases, due to cost and design constraints, the preceding examplewearable electronic device may not incorporate additional temperaturesensors which, in turn, can reduce performance of othertemperature-dependent components.

Contrasting the preceding example, a wearable electronic device asdescribed herein that includes a temperature sensing system can reduceparts use and design complexity by requiring only that a singletemperature sensor is included within the wearable electronic devicehousing. A first differential temperature probe can be routed from thetemperature sensor to the processor, a second differential temperatureprobe can be routed from the temperature sensor to the battery, and athird differential temperature probe can be routed from the temperaturesensor to another temperature-dependent component (e.g., display,biometric sensor, and so on). It may be appreciated that systems asdescribed herein can dramatically improve performance oftemperature-dependent sensors and systems, can reduce part cost, canreduce manufacturing complexity, and can reduce design constraints. In amore simple and general phrasing, embodiments described herein (1)facilitate higher performance from temperature-dependent systems ofwearable electronic devices, (2) facilitate less expensive, less complexmanufacturing of wearable electronic devices and (3) facilitate areduction in size, weight, and power consumption of wearable electronicdevices.

Further to the foregoing described advantages of a temperature sensingsystem, other embodiments described herein can position one or moreprobe locations so as to evaluate a skin or body temperature of a useror wearer of a wearable electronic device. For example, in someembodiments, a differential temperature probe can position its secondend (also referred to as a “distal” end) such that the second end isthermally coupled to a portion of the housing of the wearable electronicdevice that touches a user's skin, such as a back crystal of a smartwatch.

As a result of this constructions, the wearable electronic device canobtain a highly accurate and highly precise measurement of the user'sskin temperature which, in turn, can be leveraged for: health or fitnessrecommendations; health or fitness tracking; biometric identification;wearable device fit evaluation; and so on. It may be appreciated thatthese foregoing examples are not exhaustive. Instead, a person of skillin the art may readily appreciate that any suitable biometric purposerelated to or informed by temperature can be achieved by leveragingsystems as described herein.

In other cases, a distal end of a differential temperature probe can beexposed to the external environment (e.g., a portion of the distal endmay be disposed along a seam between two clamshell portions of thehousing). As a result of this construction, the wearable electronicdevice can obtain a highly accurate and highly precise reading oftemperature external to the electronic device.

In still further embodiments, as noted above, a single temperaturesensor can be associated with any suitable number of differentialtemperature probes in turn having respective distal ends coupled to anynumber of different internal or external parts, components, volumes, orsurfaces of a wearable electronic device. In one example, everyintegrated circuit within a wearable electronic device housing can bethermally coupled to a distal end of a different differentialtemperature probe. In this construction, each and every part within thewearable electronic device may have some operation, output, or inputcalibrated or adjusted as a function of temperature.

The preceding examples all reference a single temperature sensor and atleast one differential temperature probe having a distal end coupled toa selected probe location. This is merely one example construction of atemperature sensing system as described herein. For example, in someembodiments, multiple temperature sensors may be used, each of which mayhave or be associated with one or more differential temperature probesthat, in turn, may include distal ends that thermally couple todifferent components, surfaces, volumes, and so on with an electronicdevice housing.

In yet further embodiments, two or more temperature sensors within anelectronic device can be cross-calibrated. In particular, in suchconstructions, a first temperature sensor can thermally couple a distalend of a first differential temperature probe to a surface of a secondtemperature sensor that, in turn, couples a distal end of a seconddifferential probe to a surface of the first temperature sensor. In thismanner, different temperature sensing systems in an electronic devicehousing can be used to calibrate one another, thereby further improvingperformance of systems, sensors, or subsystems of a wearable electronicdevice.

In addition, a temperature sensing system as described herein can beleveraged in different ways when incorporated into different classes ofwearable electronic devices. For example, a smart watch may leverage atemperature sensing system to detect a temperature of a processor and aback crystal. In another example, a pair of wireless headphones orearbuds may leverage a temperature sensing system to detect atemperature of an inner ear of a wearer of those headphones or earbuds.In yet another example, a smart stylus may leverage a temperaturesensing system to detect whether a user is grasping the stylus.

The foregoing embodiments are not exhaustive of the benefits orpotential use cases for a temperature sensing system as describedherein. It may be appreciated that in different implementations, atemperature sensing system may be leveraged for a different purpose orone or more purposes than those described above.

For simplicity of description, the embodiments that follow reference awearable electronic device that incorporates a single temperaturesensing system as described herein. The temperature sensing system, asnoted above, includes a temperature sensor and a differentialtemperature probe.

For embodiments described herein, a differential temperature probe isconfigured as an in-plane thermopile implemented as an electrical seriesof thermocouples defined across a length of a high aspect ratiosubstrate. In one example, the substrate is formed from a flexiblematerial such as polyimide, although this is merely one example andother suitable flexible (or rigid) materials may be used in otherimplementations.

As a result of this construction, the substrate defines a first end(“reference” end) and a second end (the “distal” end). The distal end isseparated from the reference end by a length of the substrate, which issubstantially greater than a width (or depth) of the substrate. In manyembodiments, an aspect ratio of ten or twenty may be suitable. In othercases, higher or lower aspect ratios may be selected but it may beappreciate that for embodiments described herein, a high aspect ratio oflength relative to width is preferred.

Between the reference end and the distal end of the substrate, parallellinear electrical traces can be disposed. Alternating pairs of thesetraces can be electrically coupled to one another to define junctions atboth the reference end and the distal end of the substrate.

In a more general and broad phrasing, a differential temperature sensoras described herein can be defined by a rectilinear substrate, that istypically flexible, having a length greater than its width (e.g., anaspect ratio greater than 1). Along the flexible substrate's length, aconductive trace is formed in a serpentine pattern, alternating from(doubling back) the reference end to the distal end. In theseconstructions, alternating portions of the conductive trace are formedwith an opposite one of two conductive materials, such as metals,semiconductors, or metal alloys. In some examples, nickel alloys can beused that are non-magnetic (so as to not interfere with operations ofthe wearable electronic device and/or to not be subject to magneticinterference sources). Examples of suitable alloys can includeconstantan, nickel alloys, copper, copper alloys, and chromel. In othercases, different metals or alloys can be selected. In manyhigh-performance embodiments, a pair of different metals that exhibit anegative Seebeck coefficient can be selected.

In other examples, different shapes can be used for both the substrateand the path(s) taken by the linear traces. More specifically, in someexamples, linear traces and/or rectilinear substrates may not berequired. In some cases, a meandering trace can be used that does notfollow a particular repeating pattern or path. In other cases, a tracecan follow a repeating pattern (e.g., zig-zag, curved, scalloped, and soon) from a first end to a second end. In other cases, a pair of tracesmay generally follow a first path whereas a second pair of tracesfollows a second path. In still further examples, a substrate supportinga differential temperature probe as described herein can have a widthgreater than its length (e.g., having an aspect ratio less than 1). Anysuitable shape for a substrate and/or any suitable pattern (whetherrepeating, regular, or otherwise) can be used for traces as describedherein. Some traces can be disposed on a first surface of a substrate,whereas other traces are disposed on a second surface of the substrate.In some cases, a substrate can include internal layers onto which, orbetween which, one or more layers of traces can be disposed.

In some cases, a differential temperature probe as described herein canbe disposed on a thin-film substrate that itself includes one or morecircuits or circuit traces. For example, a flexible circuit may be usedto route signals to a particular element, such as a heating element(e.g., heated vehicle seat) or a camera element. A differentialtemperature probe as described herein can be disposed onto the sameflexible circuit. In this manner, a single flexible circuit can be usedfor both signaling purposes and temperature sensing (temperaturegradient sensing) purposes.

In this manner, the conductive trace defines a single electricallyconductive path, formed from pairs of alternating conductive materials,that is configured to leverage the Seebeck effect to generate a voltagecorresponding to a temperature difference from the reference end to thedistal end across the length of the flexible substrate. This voltage canthereafter be correlated to a temperature differential which, in turn,can be summed with a temperature output from the temperature sensor tooutput an absolute temperature of the probe location.

It may be appreciated that any suitable circuitry can be used to sampleand/or otherwise measure a voltage across leads of a conductive tracethat defines a differential temperature probe as described herein. Insome cases, leads of a differential temperature probe can beconductively coupled to an input of a temperature sensor. In otherwords, in some embodiments, a temperature sensor of a temperaturesensing system can be configured to receive, as input, a voltagecorresponding to a temperature difference between a referencetemperature measured by that temperature sensor and some arbitrary probelocation. In other cases, a separate processor and/or circuit can beconfigured to receive, as input, a voltage output from a differentialtemperature probe. In this example, the separate processor and/orcircuit can be configured to convert the measured/sampled voltage into adigital value for simplified processing.

In yet other examples, conversion of a voltage output from adifferential temperature probe can be performed in whole or in part byan analog to digital converter. In yet other examples, conversion of avoltage output from a differential temperature probe can be performed bya general purpose processor within a wearable electronic deviceincorporating the differential temperature probe.

These foregoing examples are not exhaustive; it may be appreciated thatany suitable technique, circuit, processor, software instance, analog todigital converter, or other suitable virtual or physical computingresource can be used to receive an input from a differential temperatureprobe, as described herein, and to prove as output a digital value (oranalog voltage or current, or any other suitable variable output) thatcorrelates with a temperature difference between a reference end and adistal end of that differential temperature probe. As used herein, theterm “computing resource” (along with other similar terms and phrases,including, but not limited to, “computing device,” or “processor” refersto any physical and/or virtual electronic device or machine component,or set or group of interconnected and/or communicably coupled physicaland/or virtual electronic devices or machine components, suitable toexecute or cause to be executed one or more arithmetic or logicaloperations on digital data.

Example computing resources contemplated herein include, but are notlimited to: single or multi-core processors; single or multi-threadprocessors; purpose-configured co-processors (e.g., graphics processingunits, motion processing units, sensor processing units, and the like);volatile or non-volatile memory; application-specific integratedcircuits; field-programmable gate arrays; input/output devices andsystems and components thereof (e.g., keyboards, mice, trackpads,generic human interface devices, video cameras, microphones, speakers,and the like); networking appliances and systems and components thereof(e.g., routers, switches, firewalls, packet shapers, content filters,network interface controllers or cards, access points, modems, and thelike); embedded devices and systems and components thereof (e.g.,system(s)-on-chip, Internet-of-Things devices, and the like); homeautomation devices, both stationary and mobile (e.g., thermostats, smokealarms, carbon dioxide alarms, security systems, alarm panels, homeautomation hubs, smart assistants, environmental sensors, homeappliances, remote controls, security cameras, and so on); industrialcontrol or automation devices and systems and components thereof (e.g.,programmable logic controllers, programmable relays, supervisory controland data acquisition controllers, discrete controllers, and the like);vehicle or aeronautical control devices systems and components thereof(e.g., navigation devices, safety devices or controllers, securitydevices, and the like); corporate or business infrastructure devices orappliances (e.g., private branch exchange devices, voice-over internetprotocol hosts and controllers, end-user terminals, and the like);personal electronic devices and systems and components thereof (e.g.,cellular phones, tablet computers, desktop computers, laptop computers,wearable devices); personal electronic devices and accessories thereof(e.g., peripheral input devices, wearable devices, implantable devices,medical devices and so on); and so on. It may be appreciated that theforegoing examples are not exhaustive.

As described herein, the term “processor” refers to any software and/orhardware-implemented data processing device or circuit physically and/orstructurally configured to instantiate one or more classes or objectsthat are purpose-configured to perform specific transformations of dataincluding operations represented as code and/or instructions included ina program that can be stored within, and accessed from, a memory. Thisterm is meant to encompass a single processor or processing unit,multiple processors, multiple processing units, analog or digitalcircuits, or other suitably configured computing element or combinationof elements.

These foregoing and other embodiments are discussed below with referenceto FIGS. 1-7. However, those skilled in the art will readily appreciatethat the detailed description given herein with respect to these figuresis for explanation only and should not be construed as limiting.

FIG. 1 depicts an example portable electronic device that canincorporate a temperature sensing system, such as described herein. Morespecifically, the portable electronic device is a wearable electronicdevice 100.

As noted above, a wearable electronic device is merely one exampleportable electronic device that can incorporate a temperature sensingsystem as described herein. Further, a portable electronic device ismerely one example category of electronic device that may incorporate atemperature sensing system as described herein. As such, generally andbroadly, it may be appreciated that any suitable electronic device caninclude one or more temperature sensing systems as described herein; thefollowing described embodiments relate to wearable devices only forsimplicity of description and illustration.

As shown in FIG. 1, the wearable electronic device 100 can include ahousing 102 that encloses and supports one or more internal componentsof the wearable electronic device 100. Example components that may beincluded within the housing 102 include, but are not limited to: aprocessor; a working memory; a persistent memory; a battery; a sensor orsensing system; an input system; and acoustic output system; a hapticoutput system; and so on. In addition, the housing 102 supports adisplay 104 that can be leveraged by a processor of the wearableelectronic device 100 to render a graphical user interface in order tosolicit input from a user or wearer of the wearable electronic device100.

The wearable electronic device 100 is illustrated as a smart watch thatincludes a band 106 for removably coupling to a user's wrist. It may beappreciated, however, that this is merely one example implementation ofa wearable electronic device. Other wearable electronic devices include:smart cuff devices; wireless or wired headphones or earbuds; healthmonitoring devices; medical devices; partially or entirely implanteddevices; and so on.

The wearable electronic device 100 may be configured to collect one ormore biometric data from a user/wearer of the wearable electronic device100 by leveraging one or more sensors enclosed in an internal volumedefined by the housing 102. For example, in some embodiments, thewearable electronic device 100 may be configured to leverage atemperature sensing system (not shown) to detect an absolute temperatureof a back crystal 108 that contacts the user's skin. In other examples,the wearable electronic device 100 may include a temperature sensingsystem to detect or quantify an absolute temperature of an inputcomponent that may be touched by a user, such as the linear inputcomponent 110 or the rotational input component 112. In either case, arise in temperature of the input component, as detected by a temperaturesensing system as described herein can be received as an input to thewearable electronic device 100 which, in response, can perform afunction or task.

For example, temperature information can be leveraged by the wearableelectronic device 100 for, without limitation: calibrating an internalsensor or subsystem of the wearable electronic device 100; monitoring atemperature of a processor of the wearable electronic device 100;changing a clock speed of a processor of the wearable electronic device100; changing a write speed or read speed of a working memory of thewearable electronic device 100; adjusting a display brightness based ona temperature of the display 104; performing health or fitness analysisin response to a temperature of the back crystal 108; providing a healthor fitness recommendation in response to a temperature of the backcrystal 108 exceeding a threshold; detecting a particular material typebased on a temperature of the band 106 (or a difference between atemperature of the band 106 and the housing 102); determining a healthrisk to the user based on a temperature of the housing 102 as comparedto a temperature of the back crystal 108; estimate a user's basal bodytemperature (or skin temperature or other body temperature) based on atemperature of the back crystal 108; estimate a user's basal bodytemperature (or skin temperature or other body temperature) based on aknown or predicted temperature gradient between the housing 102 and theuser's skin; measuring or estimating a user's interior wrist temperatureby determining a gradient between an external surface of the housing 102and the user's wrist; estimating a second user's basal body temperature(or skin temperature or other body temperature) based by placing aportion of the housing 102 (e.g., a front crystal) on the secondperson's forehead, ear, or other body part; and so on. It may beappreciated that these examples are not exhaustive; the wearableelectronic device 100 may be configured to leverage absolute temperaturemeasurements in a number of suitable ways.

Further, as noted above, the wearable electronic device 100 need not beimplemented as a smart watch or a wearable electronic device. In somecases, the wearable electronic device 100 can be implemented as awireless ear bud configured to rest at least partially within a user'sear canal. In such implementations, a temperature measurement fromwithin the user's ear canal can be used to determine whether the userhas an elevated or lowered body temperature. This determination can beused to evaluate basal body temperature and/or a fever condition of theuser.

The foregoing described temperature estimations/predications/estimationsthat relate to the user's basal body temperature can in turn beleveraged to generate a recommendation to the user to self-quarantine ora recommendation to the user to enable or review results of acontact-tracing application or service to determine whether an exposurerisk to a contagious virus exists (e.g., COVID-19). In still furtherexamples, medical attention can be signaled in response to determiningthat the user's temperature exceeds or falls below a threshold. In otherexamples, a user's basal body temperature can be used to estimate orpredict an ovulation pattern.

The foregoing examples are not exhaustive. A person of skill in the artmay readily appreciate that a temperature sensing system as describedherein can be leveraged in a number of ways to improve performance ofinternal components, subsystems, and sensors of the wearable electronicdevice 100 and, additionally, may be leveraged to provide health and/orfitness recommendations to a user/wearer of the wearable electronicdevice 100.

FIG. 2 depicts a simplified system diagram of a temperature sensingsystem, such as described herein, disposed within a housing of aportable electronic device 200. The portable electronic device 200 canbe any suitable portable electronic device, such as the wearableelectronic device described above in reference to FIG. 1. In othercases, the portable electronic device 200 can be implemented in adifferent manner.

The portable electronic device 200 includes a housing 202 into which atemperature sensing system as described herein is disposed. The housing202 can be coupled to and/or can include or may be partially defined bya body 204 defining an external surface. In an example in which theportable electronic device 200 is implemented as a smart watch, the body204 may be a back crystal that contacts a user's skin. In an example inwhich the portable electronic device 200 is implemented as a wirelessearbud/earphone, the body 204 may be a housing portion configured tocontact an interior surface of a user's ear canal. In yet otherimplementations, the body 204 may be implemented as another class ofelectronic device, portable device, or wearable device and the body 204may be implemented differently.

As noted above, the housing 202 of the portable electronic device 200encloses a temperature sensor 206. The temperature sensor 206 can be anysuitable circuit or integrated circuit package configured to quantifyabsolute temperature ambient to the temperature sensor 206.

The temperature sensor 206 may be implemented as a thermocouple, aresistance temperature detector, a thermistor, an optical temperaturesensor, or as a semiconductor temperature sensor or any combinationthereof. In many implementations, the temperature sensor 206 includes apurpose-configured (e.g., application-specific) processor or otherintegrated circuit configured to perform or coordinate one or moreoperations of the temperature sensor 206.

The temperature sensor 206, in many examples, is potted or otherwiseencapsulated and may be configured to detect absolute temperature of aparticular external surface thereof. In such embodiments, thetemperature sensor 206 defines a “sensing surface” that can be thermallycoupled to another component, element, or other body in order to measurean absolute temperature thereof. In the illustrated embodiment, thetemperature sensor 206 defines a sensing surface on an upper surfacethereof. As illustrated, the temperature of the sensing surface islabeled as T₁.

In this embodiment, the temperature sensing system includes a firstdifferential temperature probe, identified as the differentialtemperature probe 208, and a second differential temperature probeidentified as the differential temperature probe 210. The differentialtemperature probe 208 includes a reference end that is thermally coupledto the sensing surface. Similarly, the differential temperature probe210 includes a reference end that is thermally coupled to the sensingsurface. In this manner, the reference end of the differentialtemperature probe 208 has the same temperature, T₁, as the sensingsurface. Similarly, the reference end of the differential temperatureprobe 210 has the same temperature, T₁, as the sensing surface.

As noted with respect to other embodiments described herein, one or bothof the differential temperature probes can be formed to be at leastpartially flexible. In particular, the differential temperature probe208 is shown as curving to meet an interior surface of the body 204.More particularly, the differential temperature probe 208 can include adistal end separated from the reference end by a length of thedifferential temperature probe 208. The distal end of the differentialtemperature probe 208 can be thermally coupled to an interior surface ofthe body 204, which may have a temperature T₂. In this manner, thedistal end of the differential temperature probe 208 has the sametemperature T₂ as the body 204. As shown, an end cap region of thedistal end is positioned perpendicularly to the body 204, although itmay be appreciated that this is merely one example. In other cases, thedifferential temperature probe 208 can be further curved to meet aninterior surface of the body 204 in a parallel manner. In yet othercases, at least a portion of the distal end of the differentialtemperature probe 208 can be partially embedded into the body 204. Anysuitable configuration is suitable.

Flexibility may not be required of all embodiments. In particular, thedifferential temperature probe 210 is shown extending in a linear mannerto meet a different interior surface of the housing 202, a chosen probelocation. As with the differential temperature probe 208, thedifferential temperature probe 210 can include a distal end separatedfrom the reference end by a length of the differential temperature probe210. The distal end of the differential temperature probe 210 can bethermally coupled to the chosen probe location, which may have atemperature T₃. In this manner, the distal end of the differentialtemperature probe 210 has the same temperature T₃ as the chosen probelocation. As with the chosen probe location, an end cap region of thedistal end of the chosen probe location 210 is positionedperpendicularly to the chosen probe location, although it may beappreciated that this is merely one example. In other cases, thedifferential temperature probe 210 can be further curved to meet aninterior surface of the chosen probe location in a parallel manner. Inyet other cases, at least a portion of the distal end of thedifferential temperature probe 210 can be partially embedded into thechosen probe location. Any suitable configuration is suitable.

In this manner, and as a result of these configurations, each of thedifferential temperature probes can generate a respective voltage (suchas described above) that corresponds to the temperature differenceassociated with that particular differential temperature probe. Forexample, a first voltage generated by the differential temperature probe208 corresponds to a difference between the reference temperature T₁ andthe temperature of the body 204 T₂ whereas a second voltage generated bythe differential probe 210 correspond to a difference between thereference temperature T₁ and the temperature of the chosen probelocation T₃.

In some embodiments, the differential temperature probe 208 and thedifferential temperature probe 210 can be formed, at least in part, onthe same flexible circuit.

As a result of the foregoing describe construction, the portableelectronic device 200 can effectively and efficiently detect threetemperatures (e.g., T₁-T₃) by leveraging only a single temperaturesensor, the temperature sensor 206.

FIG. 3A depicts a differential temperature probe of a temperaturesensing system, such as described in reference to FIG. 2. In particular,the differential temperature probe 300 includes a substrate 302 having ahigh aspect ratio onto which two or more layers of different metals maybe formed. For example, as described above, the substrate 302 can be aflexible or semiflexible, substrate (e.g., polyimide, plastics,polymers, polyethylene terephthalate, polycarbonate, acrylics, liquidcrystal polymers, glass, metal, and so on) or, in certain embodimentsmay be a rigid substrate.

As noted above, a differential temperature probe such as thedifferential temperature probe 300 includes a single conductive traceformed in a serpentine pattern defined across a length thereof.

The conductive trace of the differential temperature probe 300terminates with two electrodes, a first electrode 304 and a secondelectrode 306, between which a generated voltage corresponding totemperature differentials can be measured.

In addition, the conductive trace of the differential temperature probe300 includes two sets of linear traces of conductive material thatextend from a reference end onto which the electrodes (formed from thesame material, in many examples) are defined to a distal end oppositethe reference end across a length of the differential temperature probe300. The electrodes can be formed from the same conductive material, ormay be formed from different conductive materials. Similarly, theelectrodes can be formed from the same material as a linear trace,although this may not be required. The reference end can be thermallycoupled to a sensing surface of a temperature sensor, such as describedabove in reference to FIGS. 1-2.

As with other embodiments described herein, a first set of lineartraces, formed from a first conductive material, can extend from thereference end to the distal end. For simplicity of illustrate a singlelinear trace of the first set of linear traces is identified in thefigure as the linear trace 308.

The differential temperature probe 300 also includes a second set oflinear traces, formed from a second conductive material different fromthe first conductive material, that doubles back from the first set oflinear traces. In particular, the second set of linear traces extendsfrom the distal end to the reference end. For simplicity of illustrate asingle linear trace of the second set of linear traces is identified inthe figure as the linear trace 310.

The first set of linear traces and the second set of linear traces areconductively coupled (defining junctions) at the reference end and thedistal end respectively so as to define a single continuous conductivepath between the first electrode 304 and the second electrode 306. Thesingle continuous path can be described and/or characterized by a numberN of “returns” or switchbacks that define the path. For example, a firstimplementation can include 10 returns, whereas a second implementationcan include 5 returns. As such, it may be appreciated that “turn” asdescribed herein can refer to a single thermocouple defining anadvancing trace and a returning trace joined together at a junction atthe distal end of a temperature probe as described herein.

It may be further appreciate that each turn of embodiments describedherein generate a voltage between leads thereof. In this manner, eachturn can be modeled as a temperature dependent voltage source. In thismanner, coupling multiple returns together in the manner depicted anddescribed in reference to FIG. 3A can be modeled as a series-connectedset of temperature dependent voltage sources. An example schematic isshown in FIG. 3B, which abstracts a set of returns of the differentialtemperature probe 300 into a set of voltage sources, coupled in series.For simplicity of illustration the linear trace 308 and the linear trace310 are collectively identified in FIG. 3B as the voltage source 312. Aperson of skill in the art may readily appreciate that the number ofreturns of a particular embodiment defines the voltage sensitivity andvoltage output of that embodiment in a linear manner. In other words, anembodiment implemented with 10 returns may be twice as sensitive tochanges in temperature as an embodiment implemented with 5 returns. As aresult, it may be appreciated that a number of returns selected for aparticular embodiment can vary based on sensitivity requirements and/ormanufacturing requirements; some implementations may require a firstnumber of returns, whereas other implementations may require a differentnumber of turns. In still further embodiments, sets of turns defining asingle conductive trace can be tapped in a center location or anotherlocation.

Returning to FIG. 3A, as noted above, the difference in conductivematerial between the first set of linear traces and the second set oflinear traces leverages the Seebeck effect to generate a voltage betweenthe first electrode 304 and the second electrode 306. The voltagegenerated between these electrodes corresponds directly to a temperaturedifference (ΔT) between the reference end (T₁) and the distal end (T₂).Example suitable materials for the first and second sets of lineartraces include constantan and chromel. In other cases, constantan andcopper may be used.

A differential temperature probe as described herein can be formed in anumber of ways. For example, as noted above, in some cases, thejunctions coupling the first set of linear traces to the second set oflinear traces can be vias defined through the substrate. In other cases,the second set of linear traces can be disposed over the first set oflinear traces in a successive manufacturing step.

For example, FIG. 4 depicts an assembly view of a differentialtemperature probe of a temperature sensing system, as described herein.As with the embodiment depicted in FIG. 3A, the differential temperatureprobe 400 includes a substrate 402 (which may be flexible, such as athin-film substrate) onto which a first set of linear traces 406 can bedisposed. Thereafter, a second set of linear traces 408 can be disposedin a manner or pattern such that at least a portion of each successivelinear traces of the second set of linear traces 408 conductivelycouples with a respective one trace of the first set of linear traces406, thereby defining a single conductive trace extending from areference end to a distal end, such as described above. In manyexamples, the sets of linear traces can be encapsulated with apassivation layer 410, although this may not be required of allembodiments.

These foregoing embodiments depicted in FIGS. 1-4 and the variousalternatives thereof and variations thereto are presented, generally,for purposes of explanation, and to facilitate an understanding ofvarious configurations and constructions of a system, such as describedherein. However, it will be apparent to one skilled in the art that someof the specific details presented herein may not be required in order topractice a particular described embodiment, or an equivalent thereof.

Thus, it is understood that the foregoing and following descriptions ofspecific embodiments are presented for the limited purposes ofillustration and description. These descriptions are not targeted to beexhaustive or to limit the disclosure to the precise forms recitedherein. To the contrary, it will be apparent to one of ordinary skill inthe art that many modifications and variations are possible in view ofthe above teachings.

For example, as noted above, a differential temperature probe asdescribed herein can be implemented in manners different than depictedabove in reference to FIGS. 3A-3B. For example, a high aspect ratio neednot be required in all implementations. In other examples, a rectilinearshape need not be required.

For example, FIGS. 5A-5B depict an example differential temperatureprobe that takes a low aspect ratio rectilinear shape. In particular, aswith other embodiments described herein, the temperature probe 500 aimplemented as an in-plane thermopile can be supported by a substrate502 onto which a continuous conductive path 504. The continuousconductive path 504 is defined, at least in part, by one or more returnsformed from traces of alternating conductive materials joined atjunctions defined on a first edge of the temperature probe 500 a and asecond edge of the temperature probe 500 a. In this exampleconstruction, two sections of a single return (e.g., a singlethermocouple of the in-plane thermopile) are identified as the firstsection 506 and the second section 508. As with other embodimentsdescribed herein, these conductive materials can be metals,semiconductors, metal or semiconductor alloys, or any combinationthereof.

In this construction, a temperature gradient can be measured across ashorter orthogonal dimension of the substrate 502. In particular, avoltage between a first electrode 510 (also referred to as a lead or ahot-bar pad or a solder pad) and a second electrode 512 corresponds to atemperature gradient between a top region of the continuous conductivepath 504 and the bottom of the continuous conductive path 504.

A construction such as depicted in FIG. 5A can be disposed onto and/orformed onto a substantially planar surface within an electronic devicehousing. For example, as shown in FIG. 5B, the temperature probe 500 acan be disposed onto a flat surface of an object 514. The object 514 canbe any suitable object, surface, or component that may be disposedwithin and/or may define a portion of, an electronic device or anelectronic device housing. In some examples, the object is, withoutlimitation: a sensor (e.g., temperature sensor, humidity sensor, touchinput sensor, optical sensor, depth sensor, direct or indirect time offlight sensor and so on); a camera; a battery; a processor; a backcrystal; a front crystal; a watch band; a lug insert region; a smartaccessory (e.g., stylus, trackpad, keyboard, and so on); and so on. Inthe illustrated configuration, the temperature probe 500 a is configuredto detect a temperature gradient through a thickness of the object 514from a top surface of the object 514 to a bottom surface of the object514. It may be appreciated, however, that this is merely one exampleconfiguration and that other configurations and layouts of thetemperature probe 500 a are possible.

For example, in some embodiments, the temperature probe 500 a, and inparticular, the substrate 502 can be disposed to contour to a surface,edge, or other boundary between one or more surface of the object 514 oranother object (see, e.g., FIG. 5B). For example, in some constructions,at least a portion of the temperature probe 500 a can bend around acorner or edge of the object 514. In other examples, a surface of theobject 514 may be curved, patterned, or otherwise non-planar. In suchexamples, it may be appreciated, that the temperature probe 500 a can beconfigured to follow at least one contour of the object 514.

In still further examples, the temperature probe 500 a can be at leastpartially disposed within the object 514. For example, the object may bea molded part and the temperature probe may be insert molded within theobject 514. In other cases, the object 514 may include a curablematerial, into which the temperature probe 500 a can be inserted priorto curing thereof.

In yet other examples, multiple temperature probes can be disposed ontothe object 514, in different orientations. In such constructions,different temperature gradients can be determined.

In the illustrated embodiment the first electrode 510 and the secondelectrode 512 are illustrated as being formed in-plane and in line withthe continuous conductive path 514 defining the temperature probe 500 a.This is not required of all embodiments.

For example, as shown in FIG. 5C, a temperature probe 500 b can besupported by the substrate 502. The substrate 502 in this example isformed in an L-shape. In another phrasing, the first electrode 510 andthe second electrode 512 are disposed in an orthogonal direction to asensing direction of the temperature probe 500 b, which like thetemperature probe 500 a may be through a smaller orthogonal majordimension of the substrate 502. As a result of this construction, theelectrodes can be folded over a corner or edge of the object 514, suchas shown in FIG. 5D.

It may be appreciated that non rectilinear shapes are possible beyondthe example shown in FIG. 5C and FIG. 5D. In addition, it may beappreciated that a single contiguous and/or monolithic substrate may notbe required. In some examples, a substrate as described herein caninclude one or more apertures, holes, vias, or other cutouts orthrough-cuts. Traces defining one or more continuous conductive pathscan circumscribe these cutouts, may traverse from one surface of thesubstrate to another surface of the substrate via one or more of thecutouts, may partially take the shape of a cutout (e.g., a portion of asidewall of a cutout may be a portion of a conductive material), and soon. In some cases, a series of perforations may be defined through thesubstrate to aide in manufacturing. For example, as shown in FIG. 5D, asubstrate as described herein may be configured to bend along an axis toat least a particular bend radius. In such constructions, one or moreperforations can be defined, formed, or otherwise made through thesubstrate and/or through one or more conductive traces defined on thesubstrate in order to aid in bending of the substrate along a lineformed by the perforations.

In yet further embodiments, a rectilinear or substantially rectilinearshape may not be required at all. For example, as shown in FIGS. 5E-5F,a cross-shaped temperature probe may be suitable in someimplementations. In particular, in FIG. 5E, a temperature probe 500 c isdepicted. The temperature probe 500 c is disposed onto a cross-shapedsubstrate identified as the substrate 502. A single conductive path(and/or more than one conductive paths) can be defined onto thesubstrate. In the illustrated embodiment, the single conductive pathincludes segment paths 504 a-504 d. As with preceding embodiments, avoltage can be generated between a first electrode 510 and a secondelectrode 512. It may be appreciated in view of the foregoingdescription that a voltage developed between these electrodescorresponds to an average temperature at each of the four distal ends ofeach illustrated arm segment of the cross-shaped substrate depicted inFIG. 5E. In other cases, more or fewer arms may be included. Some armsmay be rectilinear, whereas others may be curved in one direction ordimension or more than one direction or dimension. Any suitable shapecan be formed by a substrate as defined herein. In further examples, atemperature probe as described herein can be formed directly onto aninterior surface or an exterior surface of a housing portion, componenthousing, module housing, or any other suitable surface associated withan electronic device.

As a result of this example construction, the segment paths of thecross-shaped substrate can be formed to different surfaces of an object514 (see, e.g., FIG. 5F). In other cases, different segments paths canbe disposed, adhered, or otherwise formed into different surface ofdifferent objects. In yet further embodiments, different segment pathscan have different lengths, can be disposed to contour to differentsurfaces, shapes, or components, and/or may defined multiple discreteconductive paths that, in turn, are associated with different pairs ofelectrodes. In other words, a person of skill in the art may appreciatethat a single substrate can host or otherwise support two or moretemperature probes as described herein.

These foregoing example embodiments are not exhaustive. Any number ofsuitable shapes can be selected for a substrate as described herein. Inaddition, any number of suitable returns and/or conductive path segmentscan be defined. In another phrasing, any suitable number ofthermocouples can be defined in any suitable pattern to define anin-plane thermopile as described herein. For example, in someembodiments, one conductive path includes a first number of returns,whereas a second conductive path includes a second number of returns. Insuch examples, temperature averaging performed as an automatic result ofthe radially symmetrical architecture shown in FIG. 5E may be biased.For example, a first arm may have 10 returns, whereas a second arm has 5returns. In such a construction, the “average” temperature of the firstand second arm may be biased toward the temperature of the first arm. Aperson of skill in the art may readily appreciate that by varying anumber of returns on each arm of a multi-arm structure such as shown,multiple different temperatures may be approximated and/or determined.

In yet other examples, multiple folds or contours can be achieved. Forexample, as shown in FIG. 5F, distal portions of each respective arm ofthe cross-shaped substrate can be folded out (or in) to contour to asurface parallel to the upper surface of the object 514. In this manner,a cross-shaped substrate can be folded to form a self-supportingstructure.

Further to the foregoing, it may be appreciated that linear traces arenot required of all embodiments. For example, as noted above, anysuitable arbitrary pattern or path can be used. For example, anarbitrary trace path is shown in FIG. 5G. In this embodiment, atemperature probe 500 d as described herein can be defined by individualtraces made from different metal materials that may take differentshapes, may have different trace widths, and so on. In this example, aswith preceding examples, a substrate 502 supports the single conductivepath 504 that is defined between the electrodes 510 and 512. In thisexample, however, individual traces of individual returns may takedifferent paths, paths of different lengths, parallel paths,non-parallel paths, and so on. FIG. 5G is presented to emphasize thatany suitable path, pattern, and/or any suitable trace width or length orother mechanical or physical property can be used in differentembodiments.

Generally and broadly, FIGS. 6A-8 depict flow charts that correspond toexample operations of methods related to manufacturing and operating atemperature sensing system as described herein. It may be appreciated,however, that these methods are provided as examples for simplicity ofdescription and are not intended to exhaustively list all methods ofmanufacturing or all methods of operating that may apply to a system asdescribed herein.

More particularly, FIGS. 6A-7 depict flow charts that correspond toexample operations of methods related to manufacturing a temperaturesensing system as described herein. It may be appreciated thatdifferently-configured differential temperature probes may bemanufactured in different ways. For example, a first implementation of adifferential temperature probe as described herein may be manufacturedleveraging a metal lamination process, whereas another differentialtemperature probe may be manufactured leveraging a sputtering process.Example processes that may be suitable for different example embodimentsinclude, but are not limited to: physical deposition (e.g., evaporativetechniques, sputtering techniques, and so on); chemical depositiontechniques (e.g., electroplating techniques, electroless platingtechniques, chemical vapor deposition, chemical etching, and so on);intermediate/sacrificial layer techniques (e.g., photoresist, stripping,developing, and so on), Any number of suitable techniques can beemployed to form a differential temperature probe as described herein.The embodiments that follow are presented as examples.

Further, it may be appreciated that different manufacturing techniquesmay be preferred or required depending upon what substrate material isrequired of a particular implementation; forming a differentialtemperature probe over a thin-film flexible substrate may invoke adifferent manufacturing process than forming a differential temperatureprobe over a rigid silicon die. As such, it may be appreciated thatmanufacturing techniques as described herein may be modified to includedifferent steps, may substitute certain steps for other steps, or mayinclude fewer steps as appropriate given a specific implementation.

FIG. 6A is a flowchart depicting example operations of a method ofmanufacturing a differential temperature probe, such as describedherein.

The method 600 a includes operation 602 at which a substrate layer isselected and prepared for manufacturing. In many cases, the substratelayer is a rigid layer made from a material such as glass. In othercases, the substrate layer may be made from another material that iseither dielectric or conductive.

In many embodiments, the substrate layer has disposed thereon a releaselayer to assist with later operations. In some cases, a release layermay not be required (see, e.g., FIG. 6B).

The method 600 a includes operation 604 at which a first set of parallellinear traces is formed and/or disposed onto the substrate layer. Thefirst set of linear traces is disposed, in some embodiments on a firstside of the substrate from a first electrically conductive material,such as constantan. In other cases, other metals, semiconductors, ormetal alloys can be used.

In addition, the method 600 a includes operation 606 at which a secondset of parallel linear traces is formed and/or disposed onto thesubstrate layer. In some embodiments, the second set of linear traces isdisposed in an interlaced manner between the first set of linear traces.In other cases, the second set of linear traces is formed on a secondside of the substrate that is opposite to the first side.

The second set of linear traces is formed form a second conductivematerial different from the first conductive material. As noted abovethe pair of selected conductive materials can be any suitable pair thatexhibits a Seebeck coefficient with a high absolute value.

In these embodiments, the second set of linear traces and the first setof linear traces are coupled together at each of the reference end (thefirst end) and the distal end (the second end) of the differentialtemperature probe. In this manner, a single conductive trace is formedthat takes a serpentine pattern. More specifically, a first portion ofthe conductive trace is formed from the first conductive material andextends from the first end to the second end to meet a first junction. Asecond portion of the conductive trace is formed from the secondconductive material and extends from the first junction at the secondend back to the first end to meet a second junction. A third portion ofthe conductive trace is formed from the first conductive material andextends from the second junction at the first end back to the second endto meet a third junction, and so on. In this example, the first portion,the first junction, and the second junction cooperate to define a singlethermocouple among a series of thermocouples defining the thermopile. Intypical embodiments, each of the first portion, the second portion andthe third portion are parallel relative to one another but this may notbe required of all embodiments.

In some examples, the junctions formed at the first end and the secondend may be made from the first conductive material or the secondconductive material. In other cases, the junctions may be defined byvias that extend through the substrate. In these examples, the first setof linear conductive traces is defined on a first side of the substrateand the second set of linear conductive traces is define on a secondside of the substrate.

Regardless of how constructed for a particular embodiment, the method600 a further includes operation 608 at which a passivation orencapsulation layer may be disposed over each layer of metal/conductivetraces. The passivation layer prevents oxidation and provides mechanicalsupport for the conductive traces. In some cases, passivation may not berequired. The passivation layer can be made of any suitable material andmay be laminated, deposited, printed, screened, or adhered in anysuitable manner. In some examples, the passivation layer is formed fromadhesives, thin-film polyimide, thin-film polyethylene terephthalate orcombinations thereof.

A method similar to the method 600 a is depicted in FIG. 6B. Inparticular, FIG. 6B is a flowchart depicting example operations of amethod of manufacturing a differential temperature probe, such asdescribed herein. The method 600 b includes operation 610 in which athin-film substrate is selected. Unlike operation 602 of the method 600a depicted in FIG. 6A, the thin-film substrate (or any other substrateselected) is not a process substrate but is rather the final substrateonto which linear traces may be formed. In other words, the operation610 differs from operation 602 in that operation 602 includes a releaselayer which is leveraged at operation 608. By contrast, the operation610 prepares a thin-film substrate (e.g., with surface treatments,temperature control, and so on) without a release layer.

The method 600 b advances to operations 612 and 614 that, like operation604 and 606 of method 600 a, deposit a first and second set of lineartraces from different metals to leverage the Seebeck effect. It isappreciated that these sets of linear traces can be formed in anysuitable matter such as described above; this description is notrepeated.

The method 600 b also includes operation 616 at which a passivationlayer or other covering layer or a series of passivation layers aredisposed over the linear traces formed by performance of operations 612and 614.

FIG. 7 is a flowchart depicting example operations of a method ofmanufacturing a temperature sensing system, such as described herein.The method 700 begins at operation 702 at which a thin-film thermopileis formed, such as by leveraging a manufacturing technique describedherein. Thereafter, at operation 704, a first end of the thermopile iscoupled to a temperature sensor. Thereafter, at operation 706, a secondend of the thermopile is coupled to a surface defining a probe location.In one example, the surface may be an interior surface of an electronicdevice housing.

In some cases, the operation 704 and 706 may be performed in oppositeorder or simultaneously.

These foregoing embodiments depicted in FIGS. 1-4 and the variousalternatives thereof and variations thereto are presented, generally,for purposes of explanation, and to facilitate an understanding ofvarious configurations and constructions of a system, such as describedherein. However, it will be apparent to one skilled in the art that someof the specific details presented herein may not be required in order topractice a particular described embodiment, or an equivalent thereof.

Thus, it is understood that the foregoing and following descriptions ofspecific embodiments are presented for the limited purposes ofillustration and description. These descriptions are not targeted to beexhaustive or to limit the disclosure to the precise forms recitedherein. To the contrary, it will be apparent to one of ordinary skill inthe art that many modifications and variations are possible in view ofthe above teachings.

As noted above, FIG. 7 is presented herein as one example of operating atemperature sensing system as described herein. As with the method(s) ofmanufacturing referenced above, it may be appreciated that theembodiment depicted in FIG. 7 is not exhaustive of all methods ofoperating a differential temperature probe or a temperature sensingsystem as described herein.

For example, a differential temperature probe as described above istypically configured to generate an output voltage. However, in certainconstructions, an output voltage can be readily converted into a currentif applied across a known resistance. As such, it may be appreciatedthat in certain embodiments, a current input may be correlated to atemperature difference.

Further, in some constructions, a voltage output by a differentialtemperature probe can be supplied as input to a voltage controlledoscillator that, in turn, generates a periodic signal having a frequencythat depends on voltage. In certain configurations, an alternatingcurrent domain signal may be preferred to a direct current domainsignal. As such, it may be appreciated that in certain embodiments, afrequency input may be correlated to a temperature difference.

As such, more generally and broadly, it may be appreciated that acircuit as described herein can be configured in anyimplementation-specific manner to convert an output of a differentialtemperature probe into a temperature measurement. The circuit canleverage a database, a look-up table, a scalar multiplier, or any othersuitable analog or digital domain value conversion technique. In oneimplementation, a look-up table correlating temperature difference tovoltage difference may be preferred, although this is merely an example.

FIG. 8 is a flowchart depicting example operations of a method ofoperating a temperature sensing system, such as described herein. Themethod 800 includes operation 802 at which a voltage is measured acrossleads of a thermopile defining a differential temperature probe, asdescribed herein. The voltage can be measured using any suitable circuitor technique. Next, at operation 804, the method 800 advances to samplea temperature of a temperature sensor that is thermally coupled to thedifferential temperature probe. In particular, as noted above, areference end of the differential temperature probe is coupled to thetemperature sensor and a distal end of the differential temperatureprobe is coupled to a chosen probe location.

In some cases, the order of operations 804 and 802 may be reversed. Inother embodiments, operations 804 and 802 may occur substantiallysimultaneously.

The method 800 further includes operation 806 at which a temperature atthe distal end is determined based on the voltage sampled at operation802 and the temperature sampled at operation 804. In many embodimentsdetermining the distal temperature (e.g., the probe location absolutetemperature) can be performed by leveraging a lookup table thatcorrelates temperature differences to voltage values. This operation canresult in obtaining a differential temperature measurement. Thereafter,the differential temperature measurement can be summed with thetemperature sampled at operation 704, also referred to as the referencetemperature. The sum of the differential temperature and the referencetemperature represent the probe location temperature.

Thereafter, the temperature sensor (and/or another circuit coupled tothe temperature sensor) can be configured to output, as digital values,one or more of: the reference temperature; the distal temperature; thedifferential temperature; the measured voltage; or any suitablecombination thereof.

As used herein, the phrase “at least one of” preceding a series ofitems, with the term “and” or “or” to separate any of the items,modifies the list as a whole, rather than each member of the list. Thephrase “at least one of” does not require selection of at least one ofeach item listed; rather, the phrase allows a meaning that includes at aminimum one of any of the items, and/or at a minimum one of anycombination of the items, and/or at a minimum one of each of the items.By way of example, the phrases “at least one of A, B, and C” or “atleast one of A, B, or C” each refer to only A, only B, or only C; anycombination of A, B, and C; and/or one or more of each of A, B, and C.Similarly, it may be appreciated that an order of elements presented fora conjunctive or disjunctive list provided herein should not beconstrued as limiting the disclosure to only that order provided.

One may appreciate that although many embodiments are disclosed above,that the operations and steps presented with respect to methods andtechniques described herein are meant as exemplary and accordingly arenot exhaustive. One may further appreciate that alternate step order orfewer or additional operations may be required or desired for particularembodiments.

Although the disclosure above is described in terms of various exemplaryembodiments and implementations, it should be understood that thevarious features, aspects and functionality described in one or more ofthe individual embodiments are not limited in their applicability to theparticular embodiment with which they are described, but instead can beapplied, alone or in various combinations, to one or more of the someembodiments of the invention, whether or not such embodiments aredescribed and whether or not such features are presented as being a partof a described embodiment. Thus, the breadth and scope of the presentinvention should not be limited by any of the above-described exemplaryembodiments but is instead defined by the claims herein presented.

The present disclosure recognizes that personal information data,including biometric data, in the present technology, can be used to thebenefit of users. For example, the use of biometric authentication datacan be used for convenient access to device features without the use ofpasswords. In other examples, user biometric data is collected forproviding users with feedback about their health or fitness levels.Further, other uses for personal information data, including biometricdata, that benefit the user are also contemplated by the presentdisclosure.

The present disclosure further contemplates that the entitiesresponsible for the collection, analysis, disclosure, transfer, storage,or other use of such personal information data will comply withwell-established privacy policies and/or privacy practices. Inparticular, such entities should implement and consistently use privacypolicies and practices that are generally recognized as meeting orexceeding industry or governmental requirements for maintaining personalinformation data private and secure, including the use of dataencryption and security methods that meets or exceeds industry orgovernment standards. For example, personal information from usersshould be collected for legitimate and reasonable uses of the entity andnot shared or sold outside of those legitimate uses. Further, suchcollection should occur only after receiving the informed consent of theusers. Additionally, such entities would take any needed steps forsafeguarding and securing access to such personal information data andensuring that others with access to the personal information data adhereto their privacy policies and procedures. Further, such entities cansubject themselves to evaluation by third parties to certify theiradherence to widely accepted privacy policies and practices.

Despite the foregoing, the present disclosure also contemplatesembodiments in which users selectively block the use of, or access to,personal information data, including biometric data. That is, thepresent disclosure contemplates that hardware and/or software elementscan be provided to prevent or block access to such personal informationdata. For example, in the case of biometric authentication methods, thepresent technology can be configured to allow users to optionally bypassbiometric authentication steps by providing secure information such aspasswords, personal identification numbers (PINS), touch gestures, orother authentication methods, alone or in combination, known to those ofskill in the art. In another example, users can select to remove,disable, or restrict access to certain health-related applicationscollecting users' personal health or fitness data.

1. A differential temperature sensor probe for a temperature sensor of aportable electronic device, the temperature sensor probe comprising: athin-film substrate defining: a first end thermally coupled to thetemperature sensor; and a second end thermally coupled to a surfacewithin the portable electronic device; and an in-plane thermopiledisposed on the thin-film substrate and comprising a conductive tracedisposed in a serpentine pattern defined between the first end and thesecond end to define an array of thermocouples conductively coupled inseries; wherein the in-plane thermopile is conductively coupled to thetemperature sensor and is configured to generate a voltage correspondingto a temperature difference between the temperature sensor and thesurface.
 2. The differential temperature sensor probe of claim 1,wherein the serpentine pattern is defined by: a first array of parallelconductive traces extending from the first end to the second end; asecond array of parallel conductive traces extending from the first endto the second end and parallel to the first array of parallel conductivetraces.
 3. The differential temperature sensor probe of claim 2, whereinthe thin-film substrate defines: a first planar surface; and a secondplanar surface opposite the first planar surface; wherein the firstarray of parallel conductive traces is disposed on the first planarsurface; and the second array of parallel conductive traces is disposedon the second planar surface.
 4. The differential temperature sensorprobe of claim 3, wherein the in-plane thermopile comprises: a firstarray of vias defined through the first end of the substrate from thefirst planar surface to the second planar surface, each via conductivelycoupling one respective conductive trace of the first array with onerespective conductive trace of the second array; and a second array ofvias defined through the second end of the substrate from the firstplanar surface to the second planar surface, each via conductivelycoupling one respective conductive trace of the first array with onerespective conductive trace of the second array.
 5. The differentialtemperature sensor probe of claim 2, wherein: each trace of the firstarray of parallel conductive traces is formed from a first conductivematerial; and each trace of the second array of parallel conductivetraces is formed from a second conductive material.
 6. The differentialtemperature sensor prove of claim 5, wherein the first conductivematerial is constantan and the second conductive material is selectedfrom chromel or copper.
 7. The differential temperature sensor probe ofclaim 1, wherein the thin-film substrate is formed from a flexiblematerial.
 8. The differential temperature sensor probe of claim 1,wherein the thin-film substrate has an aspect ratio greater than orequal to two.
 9. The differential temperature sensor probe of claim 1,wherein the surface is an interior surface of a housing of theelectronic device.
 10. The differential temperature sensor probe ofclaim 1, wherein the surface is an exterior surface of a housing of theelectronic device.
 11. The differential temperature sensor probe ofclaim 1, wherein the thin-film substrate is formed from one or morematerials in a group consisting of: polyimide; polyethyleneterephthalate; polycarbonate; plastics; acrylics; and liquid crystalpolymers.
 12. The differential temperature sensor probe of claim 1,wherein the in-plane thermopile further comprises a passivation layerdisposed over the conductive trace.
 13. A temperature sensing system foran electronic device, the temperature sensing system comprising: atemperature sensor defining an exterior surface; and a differentialtemperature probe having a high aspect ratio and formed from a thin-filmmaterial, the differential temperature probe comprising: a flexiblesubstrate defining: a first end thermally coupled to the exteriorsurface of the temperature sensor; a second end separated from the firstend by a length of the differential temperature probe; and a conductivetrace defining a conductive path between a pair of leads disposed on thefirst end, the conductive trace disposed in a serpentine pattern betweenthe first end and the second end, the conductive trace comprising: afirst set of traces disposed from a first conductive material extendingfrom the first end to the second end; and a second set of tracesdisposed from a second conductive material extending from the second endto the first end; wherein a voltage difference between the pair of leadscorresponds to a temperature difference between the exterior surface andthe second end of the differential temperature probe.
 14. Thetemperature sensing system of claim 13, wherein: the temperature sensoris conductively coupled to the pair of leads of the conductive trace ofthe differential temperature probe; and the temperature sensor isconfigured to provide: a first output corresponding to a firsttemperature of the exterior surface; and a second output correspondingto a second temperature of the second end of the differentialtemperature probe.
 15. The temperature sensing system of claim 13,wherein the first output and the second output are digital values. 16.The temperature sensing system of claim 13, wherein the first conductivematerial and the second conductive material different selections fromthe group consisting of: nickel alloys; constantan; chromel; andsemiconductors.
 17. The temperature sensing system of claim 13, whereinthe first set of traces is disposed on a first surface of the flexiblesubstrate and the second set of traces is disposed on a second surfaceof the flexible substrate, the second surface opposite the firstsurface. 18-20. (canceled)
 20. The method of claim 19, comprising:providing as output from the temperature sensor, the first temperature,the second temperature, and the third temperature.
 21. A portableelectronic device, comprising: a display; a housing that supports thedisplay; and a temperature sensing system disposed within the housing,the temperature sensing system comprising: a temperature sensor; and afirst temperature probe, the first temperature probe comprising: athin-film substrate defining: a first end thermally coupled to thetemperature sensor; and a second end thermally coupled to a surface ofor within the housing; and an in-plane thermopile disposed on thethin-film substrate and comprising a conductive trace disposed in aserpentine pattern defined between the first end and the second end todefine an array of thermocouples conductively coupled in series; whereinthe in-plane thermopile is conductively coupled to the temperaturesensor and is configured to generate a voltage corresponding to atemperature difference between the temperature sensor and the surface.22. The portable electronic device of claim 21, wherein the thin-filmsubstrate is folded.
 23. The portable electronic device of claim 22,further comprising a second temperature probe thermally coupled to thetemperature sensor.